The present invention pertains to the field of hardware for connecting devices, such as a mouse and a keyboard, to a computer, and in particular, to extender hardware (including intelligent systems) to be used in combination with the device connection hardware for providing for connections of such devices over substantially greater distances than the device connection hardware allows by itself.
In order to allow for easier connection to a personal computer (PC) of input/output devices, such as a mouse and a keyboard, a standard has been developed to replace the existing so-called Personal System 2 (PS2) standard for such devices. The new standard is called universal serial bus (USB), and its latest version (2.0) sets out how not only low speed devices such as a mouse or keyboard are to be connected, but also how high speed devices such as a digital camera or a scanner are to be connected. USB allows expandability of a PC""s capabilities via an external port, eliminating the need for users or integrators to open the system chassis of the PC. USB supports multiple peripheral devices simultaneously, so it allows users to run numerous devices such as printers, scanners, digital cameras and speakers from a single PC. USB also provides for automatic device detection and installation (i.e. plug-and-play).
In providing a specification that would make connection of a device easier (via plug-and-play) and at the same time providing for a connection that is up to 100 times faster than the original serial port and supports multiple device connectivity, tradeoffs had to be made. One tradeoff is in the maximum allowed length of the connector used to connect a peripheral device to a computer; the cable for a USB peripheral device cannot be greater than 5 meters, although it is possible to connect to a computer up to thirty meters away using for example a series of so-called hub devices or driving the connection at a higher-than-designed-for voltage.
In some applications, it is advantageous to connect a peripheral device, such as a mouse or keyboard, to a computer over distances of up to 10,000 feet. It is not possible to make such a connection using a series of hubs (because USB hub hardware makes possible a connection of only up to thirty meters even using hubs), nor does the prior art generally teach how to make a USB connection over such long distances.
What is needed is a way of extending a connection from a USB peripheral device, or at least a low-speed USB peripheral device such as a mouse or a keyboard, to distances of up to 10,000 feet.
Accordingly, the present invention provides a system for extending in length a connection from a universal serial bus (USB) peripheral device to a computer beyond the length enabled by the device hardware, the system including: a USB host emulator, for polling the USB peripheral device according to a USB standard protocol, for receiving input provided by the USB peripheral device in response to the polling, for providing the input in a form suitable for transmission via a communications channel, such as serialized form for transmission via a copper or spread spectrum form for communication as a radiofrequency signal; the communications channel, having an input end and an output end, responsive to the input at the input end, for providing the input at the output end; a USB device emulator, responsive to the input at the output end of the communications channel, and further responsive to polling from the computer, and in response to the polling, for reforming the input into USB format and providing the USB formatted input to the computer according to a USB protocol.
In a further aspect of the invention, the USB host emulator includes: a USB transceiver, for bi-directionally coupling a glue logic module to the USB peripheral device so as to allow polling the USB peripheral device and to allow receiving a report packet provided by the USB peripheral device in response to the polling, the USB transceiver for providing physical interfacing, according to a USB standard, of the attached USB device to the glue logic module; the glue logic module, such as a field programmable gate array, for interfacing the USB transceiver to a control processor; a control processor, for polling the USB peripheral device and for receiving a report packet provided by the USB peripheral device in response to the polling, and further for providing the report packet information in serialized form; a serial peripheral interface (SPI) universal asynchronous receiver/ transmitter (UART), serving as a bus for serial data transmission, for applying the serialized report packet information to a communications port; and the communications port, for applying the serialized report packet information received from the SPI UART to the communications channel.
In another, further aspect of the invention, the USB device emulator includes: a communications port, for receiving the serialized report packet information received from the SPI UART to the communications channel; a serial peripheral interface (SPI) universal asynchronous receiver/transmitter (UART), serving as a bus for serial data transmission, for communicating the serialized report packet information to a control processor; the control processor, for receiving and storing the serialized report packet information, responsive to polling from the host computer, for providing the report packet information in packetized format in response to the polling; the glue logic module, such as a field programmable gate array, for interfacing the control processor to a USB transceiver; and the USB transceiver, for bi-directionally coupling the glue logic module to the host computer so as to allow polling of the USB peripheral device and to allow providing a report packet provided by the USB peripheral device in response to the polling, the USB transceiver for providing physical interfacing, according to a USB standard, of the host computer to the glue logic module.